Electronic structure of new quaternary superconductors LaONiBi and LaOCuBi from first principles

TL;DR

This study uses first-principles calculations to analyze the electronic structure of newly synthesized LaONiBi and LaOCuBi superconductors, revealing their covalent and ionic bonding characteristics and their potential as low-Tc superconducting ionic metals.

Contribution

First comprehensive electronic structure analysis of LaONiBi and LaOCuBi, the first bismuth-containing quaternary oxypnictides, providing insights into their bonding and conduction properties.

Findings

Bonding within layers is covalent, between layers is ionic.

Fermi surfaces are two-dimensional, indicating anisotropic conduction.

Main states at Fermi level originate from (Ni(Cu)-Bi) layers.

Abstract

Based on first-principles FLAPW-GGA calculations, we have investigated the electronic structure of newly synthesized novel superconductors LaONiBi and LaOCuBi, the first bismuth-containing compounds from the family of quaternary oxypnictides which attract now a great deal of interest in search for novel 26-55K superconductors. The band structure, density of states and Fermi surfaces are discussed. Our results indicate that the bonding inside of the (La-O) and (Ni(Cu)-Bi) layers is covalent whereas the bonding between the (La-O) and (Ni(Cu)- Bi) blocks is mostly ionic. For both oxybismuthides, the DOSs at the Fermi level are formed mainly by the states of the (Ni(Cu)-Bi) layers, the corresponding Fermi surfaces have a twodimensional character and the conduction should be strongly anisotropic andhappen only on the (Ni(Cu)-Bi) layers. As a whole, the new oxybismuthides may be described as low-TC superconducting non-magnetic ionic metals.